Documents published in Scipedia

• Multifunctional materials for SHM diagnosis and structural performance assessment

  C. García, B. Fernandes, R. Mendes, F. Otero

  Fibregy OA (2024). Vol. Public Deliverables, 20

  
  

  Abstract

  This report will evaluate the structural health monitoring (SHM) methodology developed in the framework of FIBREGY to obtain the damage state of the fibre-based structural elements used in offshore platforms. The non-destructive vibration-based methodology deals with the variations of the key performance indicators (KPIs, e.g. overall vibration energy, damping, etc.) which are influenced by the presence of damage in the FRP materials. To assess the damage state of the multifunctional materials, a set of sensors and/or optical fibers will be interleaved in the interlaminar regions of the FRP-based materials used in the marine structures. Initially, the main scope of this report is to explore the selection of the most suitable sensors to manufacture the multifunctional materials. Subsequently, the mechanical performance of the multifunctional materials will be analyzed with the paramount purpose to evaluate the possible weakness of the material induced by the embedding of the sensor. Last, it will be considered the testing of different specimens of multifunctional materials and the preparation of the best strategy for the validation of the monitoring system in a real-case through one of the WP6 demonstrators (FRP-based towers).

  Abstract
  This report will evaluate the structural health monitoring (SHM) methodology developed in the framework of FIBREGY to obtain the damage state of the fibre-based structural [...]

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• Connections in offshore structures

  B. Fernandes, J. Nuno-Silva, J. Cardoso, M. Moutinho, F. Otero, P. Ropero, O. Chan Taw, R. Mendes

  Fibregy OA (2024). Vol. Public Deliverables, 19

  
  

  Abstract

  Report containing a benchmark of the connection technologies in OWTP structures, their respective evaluation and selection. The report will also include the re-design and optimization of the most promising connections, supported by a detailed description of the experimental testing campaign.

  Abstract
  Report containing a benchmark of the connection technologies in OWTP structures, their respective evaluation and selection. The report will also include the re-design and optimization [...]

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• Environmental protection of composites

  O. Chan Taw, A. Comer, N. Goutay, F. Otero

  Fibregy OA (2024). Vol. Public Deliverables, 18

  
  

  Abstract

  The report of deliverable D2.3 includes all the results of the durability tests performed during the extensive experimental campaign. The most relevant laboratory tests to evaluate the environmental performance of the various solutions are listed below: - Alternate and continuous immersion in salt solution (ISO 11130, ISO 2812) - High Humidity Test (ISO 6270) - 500 hours at 40 °C and 98 % HR - QUV accelerated weathering test (ISO 11507) - 1000 hours with cycles of 4 hours UV light / 4 hours of high humidity - Climatic chamber with thermal cycles (-20°C / + 80°C) - Adhesion tests: Cross Cut (ISO 2409) and Pull Off (ISO 4624) before and after each ageing test - Gloss (ISO 2813) and Colorimetry (ISO 7724) measurements before and after each ageing test - Observation of visual defects before and after each ageing test - The effect on the texture on biofouling will be evaluated at coupon level in natural sea water basin A dedicated Design of Experiments (DOE) will be built to optimize the number of samples to be tested. The durability will be evaluated for the following configurations: - At least 2 paint references (from 2 suppliers or 2 different chemistries) - At least 2 composite substrates (1 thermoset and 1 thermoplastic) - Three types of application: adhesive paint film, in-mold application of paint film and stand ard liquid paint application - Three surfaces textures: flat surface and two fouling release textures - Unprotected composite samples as a comparison

  Abstract
  The report of deliverable D2.3 includes all the results of the durability tests performed during the extensive experimental campaign. The most relevant laboratory tests to [...]

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• Fatigue performance of composites

  A. Comer, A. Hejjaji, G. Bhatia, J. R. Pothnis, J. Cardoso

  Fibregy OA (2024). Vol. Public Deliverables, 17

  
  

  Abstract

  The deliverable will present the results and conclusions of the different fatigue tests to be performed. An interim report will be delivered by month M24 describing the regular fatigue tests (O° and 90° lay-ups) and results. This data is the only one required by the numerical models for material calibration. The report will be completed by M29, including the advanced fatigue characterization performed on oblique (45°) lay-ups and also the connections.

  Abstract
  The deliverable will present the results and conclusions of the different fatigue tests to be performed. An interim report will be delivered by month M24 describing the regular [...]

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• Ongoing development of applications of the Cone Penetration Test in interpretation and design

  B. Lehane*

  ISC2024.

  
  

  Abstract

  This paper presents recent research on the application of the cone penetration test to site characterisation and foundation design. Aspects considered related to characterisation include the interpretation of relative density in granular soils, the derivation of the penetration-velocity characteristic, corrections for shallow penetration and scale effects in laboratory experiments and the influence of particle size on penetration resistance. In relation to foundation design, the paper outlines the nature of CPT-based correlations and describes the development of three types of such correlations for footings, axially loaded piles and laterally loaded piles.

  Abstract
  This paper presents recent research on the application of the cone penetration test to site characterisation and foundation design. Aspects considered related to characterisation [...]

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• The influence of soil structure on CPTu and SDMT results

  S. Oberhollenzer*, E. Lande, S. Ritter

  ISC2024.

  
  

  Abstract

  The natural structure of clays has a significant influence on its mechanical behaviour and can be characterized using insitu and laboratory tests. It was reported by Robertson (2016) that soil structure leads to an increased tip resistance (qc) and shear wave velocity (Vs) when performing seismic cone penetration tests. However, only limited studies investigated changes in soil structure by means of in-situ tests. Sensitive, marine clays were investigated within the research project "VIBE – Sustainable Ground Improvement Solution for Oslo" at the Norwegian Geo-Test site Onsøy (Gundersen et al. 2019). Possibilities and limitations of the vibro replacement method were studied for very soft ground conditions based on a full-scale field test. The influence of soil structure on in-situ measurements of piezocone penetration tests (CPTu) and seismic flat dilatometer tests (SDMT) are further studied by intentionally disturbing the soil structure by a vibrator. Results of CPTu and Medusa SDMT, executed before and after treatment, are compared to characterize changes in soil structure. The results indicate that the vibration-induced destructuration led to a significant decrease of CPTu measurements, namely tip resistance (qc), sleeve friction (fs) and measured pore pressure (u2), within medium to high sensitive clays. As the decrease in fs is more significant compared to the decrease in qc, a significant decrease in friction ration (Rf) was observed. In analogy, SDMT resulted in a decrease in shear wave velocity (Vs), horizontal stress index (KD) and dilatometer modulus (ED) after the vibro treatment. It was further shown that the soil behaviour type chart according to Robertson (2016) leads to no sufficient characterization of soil structure in soft, marine clays.

  Abstract
  The natural structure of clays has a significant influence on its mechanical behaviour and can be characterized using insitu and laboratory tests. It was reported by Robertson [...]

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• BRIGHT SPARK LECTURE - A Machine Learning Paradigm for Subsurface Stratigraphy from Sparse Data

  C. Shi*

  ISC2024.

  
  

  Abstract

  Subsurface stratigraphy is an indispensable component of geotechnical site characterization and primarily deals with the interpretation of geological interfaces from site-specific measurements, such as boreholes. Traditional geological profiling methods often rely on engineering judgement for manual drawing or entirely depend on parametric models for interpolation. Both approaches face challenges when dealing with limited geo-data. To effectively address the dilemma, a new machine learning paradigm is proposed in this study to combine valuable prior geological knowledge and sparse site-specific measurements for data-driven predictions of both two-dimensional geological cross-sections and threedimensional geological domains. The valuable prior knowledge is quantitatively represented as training images, which are compiled and stored in a training image database that is further enriched and augmented by employing deep generative models. Subsequently, the optimal training images that are compatible with the available site-specific data are adaptively selected for onward stochastic predictions under the framework of non-parametric Bayesian analysis. The method has been successfully applied to tackle geological profiling challenges in Hong Kong. The proposed framework is demonstrated to be capable of not only predicting the most probable geological patterns but also effectively quantifying associated stratigraphic uncertainty. The framework holds great potential of revolutionizing current engineering practices

  Abstract
  Subsurface stratigraphy is an indispensable component of geotechnical site characterization and primarily deals with the interpretation of geological interfaces from site-specific [...]

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• Interpretation of Cone Penetration Tests in Gravelly Soil

  K. Rollins*, J. Roy, A. Walburger, S. Amoroso, R. Dhakal, L. Minarelli, L. Marenghi

  ISC2024.

  
  

  Abstract

  Although gravelly soils have been observed to liquefy in 27 earthquakes in the past 120 years, many engineers believe that gravel cannot liquefy due to its high hydraulic conductivity. Gradations from gravel liquefaction case histories have shown these deposits typically contain 25 to 40% sand, reducing the hydraulic conductivity and enabling excess pore pressures to cause liquefaction. While cone penetrometers (CPT), typically used to evaluate liquefaction resistance in sand, may show increases in penetration resistance due to their small diameter relative to gravel particles, the CPT has successfully predicted gravel liquefaction for looser sandy gravels. Case histories in Wellington, New Zealand demonstrate the successful identification of gravel liquefaction hazards using CPT. Although some layers in the profile indicated high penetration resistance, most of the profile was correctly predicted to liquefy. The Soil Behavior Type (SBT) from the CPT did not consistently indicate a sandy gravel profile but was often classified as behaving like a sand or silty sand; likely influenced by higher sand percentages between gravel particles. To evaluate the ability of the CPT to characterize gravelly soils and their liquefaction potential, additional field case histories are desirable. This paper presents test results from two case histories, one in Wellington, New Zealand, and one in Petrinja, Croatia, where gravels have liquefied. In both cases, the CPT occasionally overestimated liquefaction resistance in gravel layers. The advantages of using a 74 mm diameter Dynamic Cone Penetrometer (DPT) are also highlighted with companion testing.

  Abstract
  Although gravelly soils have been observed to liquefy in 27 earthquakes in the past 120 years, many engineers believe that gravel cannot liquefy due to its high hydraulic [...]

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• Quantitative Assessment of Tip Saturation for High Quality Piezocone Testing

  I. Rocchi*, L. Tonni, G. Gottardi

  ISC2024.

  
  

  Abstract

  The research compares 2 CPTU profiles obtained with a same piezocone setup but having a different degree of saturation associated with the pore pressure measuring system. In the reference test, saturation was performed injecting 20cS silicon oil in the conduit connecting the porous stone to the pressure sensor and applying vacuum while submerged in oil for 15 minutes. The piezocone tip was then assembled with a saturated porous stone while submerged in oil. In the other test, the degree of saturation was purposely lowered by introducing air in the same conduct, whereas all other saturation steps were unchanged. The degree of saturation was compared quantitatively by measuring an analogue of the Skempton’s coefficient B, which is routinely used in laboratory testing to assess specimen saturation in a triaxial cell. The value associated with the saturation condition was measured employing a tool specifically designed for this purpose. The saturation procedures adopted were selected based on preliminary experimental activity in the laboratory, which provided target values of the pore pressure parameter corresponding to full or partial saturation. The CPTUs were performed at a test site presenting 10m clay unit followed by sand. The profiles measured were compared in terms of pore-pressure profiles, as well as the influence this had on corrected tip resistance, Soil Behaviour Type classification and mechanical properties. Additionally, a dissipation was performed for each test to compare consolidation parameters.

  Abstract
  The research compares 2 CPTU profiles obtained with a same piezocone setup but having a different degree of saturation associated with the pore pressure measuring system. [...]

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• Calibration Chamber Testing on Tailings for Interpretation of Partially Drained CPT

  M. Ghafghazi, L. Qi*, H. Zhao, W. Liu, M. Etezad, J. Sharp, M. Talesnick

  ISC2024.

  
  

  Abstract

  The Cone Penetration Test (CPT) is the primary site investigation tool in silt-rich tailings. The permeability and compressibility range of tailings often puts the standard CPT penetration rate in the partial drainage range where the tip resistance, pore water pressure, and sleeve friction become functions of not only the state, but also drainage conditions. This makes interpretation of the state parameter, which represents liquefaction susceptibility and residual strength of tailings particularly challenging. It is not clear whether existing CPT interpretation frameworks are capable of accounting for effects of partial drainage. Developing field correlations for interpreting partially drained CPT data in tailings is hampered by spatial variability and sampling disturbance. CPT tests were performed in a calibration chamber and in the field on a gold tailings material. Dissipation tests were performed, and the pore water pressures on the cone at the u2 position were monitored. The degree of partial drainage was estimated based on the coefficient of consolidation inferred from these dissipation tests. Similarities and differences of the calibration chamber and field CPTs were discussed.

  Abstract
  The Cone Penetration Test (CPT) is the primary site investigation tool in silt-rich tailings. The permeability and compressibility range of tailings often puts the standard [...]

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